Add template for questions without answers

docs/_includes/options-new/not-written.html

@@ -0,0 +1,3 @@
+<div class="alert alert-info">
+  This answer to this question has not yet been written. You can <a href="https://github.com/select2/select2/blob/master/docs/README.md#how-can-i-fix-an-issue-in-these-docs">improve this documentation</a> by creating a pull request with an answer to this question.
+</div>